Genesis
by Bluetech
Summary: This story is a non-fictional investigation of a topic I happened to think about a month or so ago. I figured it would improve your comprehension of said topic and make Rio 2 more relatable. Given my admiration for birds and scientific mindset, I strive for accuracy and realism. I enjoy understanding how and why things work in nature and applying this knowledge in films like this.


**I have ceased uploading not because my desire to write has waned, but rather I cannot spare the time to create anything satisfactory. Though this does not mean my hiatus is over, I wanted to contribute a quick story on a subject that, as far as I know, has not been written about previously.**

 **Enjoy and feel free to share your thoughts, as they are always welcome.**

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 **Genesis**

Tiago, Bia, and Carla are, without a doubt, the three greatest gifts Blu and Jewel have ever received. How, then, were they transformed from mere possibilities in their parents' minds into a trio of testaments to the wondrous nature of life itself?

At first glance it may be interpreted as a purely philosophical inquiry, a complex question lacking strictly valid answers and one that every individual may answer differently.

For the sake of simplicity, I will stray away from theoretical dialogue and instead provide a strictly biological explanation.

Before we begin, allow me to briefly explain how the precursors of offspring in the animal world arise. Consider it a refresher on the topic, which hopefully you were taught in high school or its equivalent, if you were not raised in the US.

Meiosis is responsible for producing sperm and egg cells, collectively referred to as gametes. Meiosis of a diploid parent cell (containing two sets of chromosomes) gives rise to four daughter cells that are haploid (containing a single set of chromosomes).

Having jogged your memory, I will now describe how offspring themselves are created in a familiar organism, the human being.

Humans, which belong to the class Mammalia, employ an XY sex determination system.

Males typically possess one X and one Y chromosome and are labeled the heterogametic sex. Females usually possess a pair of X chromosomes and are the homogametic sex.

After one meiotic cycle, a given sperm cell will receive either an X or Y chromosome. In contrast, an egg cell will always end up with X chromosome.

When a sperm cell and egg cell meet and fertilization occurs, the former gamete will donate either an X or Y chromosome to the latter gamete containing an X chromosome.

Therefore, the gender of human children is determined by the male. Probability, of course, has the final say in the matter.

It is time for me to discuss the second and final example, the crux of this treatise, in the context of avian beings.

Birds, constituting the class Aves, utilize the WZ sex-determination system instead.

It must be noted that this is the merely the agreed-upon naming convention and doesn't reflect actual chromosome shape.

This system is essentially the inverse of that which exists in mammals. Male birds possess two Z chromosomes and are homogametic. Females possess one W and one Z chromosome and are heterogametic.

Once meiosis has taken place, each sperm cell will harbor a Z chromosome while each egg cell may harbor either a W or Z chromosome. When fertilization occurs, a W or Z egg will absorb a Z sperm. In this case, females dictate the gender of their progeny. Probability, again, makes the final choice.

Armed with this knowledge, we can now apply it in logical fashion to a certain macaw couple we have come to admire.

In the wake of Blu and Jewel's intimate encounter, three lucky sperm cells managed to survive the journey up her reproductive tract and fuse with three receptive egg cells.

Two of those delivered their W chromosome payloads to two receptive ova. These would thus develop into Bia and Carla.

The last sperm cell, with its Z chromosome payload, would encounter the third available egg. Their union would lead to the development of Tiago.

With that, we have arrived the conclusion of this exploratory tale. Let it be known that the mystery has been officially unraveled.

Where sexual reproduction is concerned, it is the ultimate duty of the male to pass his genes on to the next generation.

Jewel embraced Blu's amorous advances and enabled him to fulfill the most important task he was charged with.

The blessing of children has been bestowed upon them, and there exists no greater boon in life.

For those of you who have pondered the topic described above or, were not exposed to it by your education system, I hope this proved to be a satisfying and insightful read.


End file.
